• Korean journal of food and cookery science
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• v.12 no.1
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• pp.20-26
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• 1996

The present study was attempted to investigate and to evaluate various hydrocolloids as a stabilizer in improving texture of the frozen yogurt. Four kinds of hydrocolloids used in this study were CMC (carboxymethyll cellulose), PGA(propylene glycol alginate), LMP(low methoxyl pectin), and the combination of LBG(locust bean gum) and GG(guar gum). The viscosity of frozen yogurt mixes did not show any significant differences among four samples at 5$^{\circ}C$. However, as the temperature increased up to 50$^{\circ}C$, theviscosity of frozen yogurt mixes containing CMC, LMP, PGA decreased drastically except frozen yogurt containing the combination of LBG+GG. The overrun of frozen yogurt containing each hydrocolloid gradually increased and reached to about 53, 50, 54, and 35%, respectively, after 40 min of operating ice cream freezer. As the result of sensory evaluation in the texture of frozen yogurt and melt-down quality, the sample containing LMP was described as the most coarce & icy, crumbly, and sand-like characters. On the other hand, PGA sample was evaluated as not being icy, crumbly, but being chewy and soft in texture. However, any significant differences among four samples were not shown in melt-down quality.

• Korean journal of food and cookery science
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• v.20 no.6 s.84
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• pp.658-666
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• 2004

In order to develop and commercialize high quality frozen soy yogurt, the effects of industrial proteases and commercial mixed cultures were examined on the functional properties and the sensory attributes of frozen soy yogurt. For quality improvement, soy protein isolates were primarily hydrolyzed by either Flavourzyme or Neurtrase, industrial Proteases, to reduce the beany flavor and increase the functional properties of the protein. The viable cell count of lactic acid bacteria was higher in the soy protein hydrolysates than whenuntreated. ABT-5 (L. acidophilus, Bifidobacterium lactis, and S. thermophilus) resulted in higher acid tolerance, bile acid tolerance and melt-down percent values than those with YC-X11 (Lactobacillus bulgaricus and Streptococci thermophilus). The overrun of frozen soy yogurt was improved by both Flavourzyme $(193.3\%)$ and Neurtrase $(156.7\%)$ treatments. With regard to thesensory characteristics, Flavourzyme improved the beany flavor, astringency taste, mouth feel and overall quality of frozen soy yogurts fermented with ABT-5. Further studies onproduct formulation will be needed to commercialize the frozen soy yogurt for the market.

• Korean journal of food and cookery science
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• v.21 no.1 s.85
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• pp.18-23
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• 2005

The effects of soybean oil and cyclodextrin were studied on the quality characteristics and storage of frozen soy yogurt prepared from proteolytic soy protein isolate. The viscosity and overrun of frozen soy yogurt were improved by the addition of soybean oil and cyclodextrin. Upon the addition of cyclodextrin, there was a decrease in the peroxide value of yogurt with subsequent increase by the addition of soybean oil during frozen storage. During the process of storage, there was an increase in the acetone and diacetyl contents, but methanol, ethanol and butanol contents decreased. However, the value of hexanal content was not consistent in the obtained results. Sensory characteristics of frozen soy yogurt such as mouth feel, and overall quality were improved by the addition of cyclodextrin and remained the same frozen storage at $-20^{\circ}C$ for 30 days.

• Korean journal of food and cookery science
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• v.21 no.2 s.86
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• pp.217-224
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• 2005

The storage characteristics of frozen soy yogurt prepared with hydrolyzed soy protein isolates were evaluated. In order to facilitate lactic fermentation bacteria grow and produce lactic acid as fast rate as possible, soy protein isolate(SPI) was hydrolyzed using two kinds of proteases; bromelain and a-chymotrypsin. The cultural systems employed thereafter for lactic fermentations were Bifidobacterium bifidum or B. bifidum and Lactobacillus bulgaricus. The viable cell counts, normal- and bile acid tolerances from the mixed cultures of B. bifidum and L. bulgaricus decreased sharply during the initial first 3 days of frozen storage and then showed a gradual decrease thereafter. Melt-down percent of the all frozen products have been favorably affected as was shown by less melting at raised testing temperature during 28 days of frozen storage except for the initial 3 days during which a minor change has been observed. Among the various volatile flavor components, the contents of acetaldehyde, acetone, diacetyl and methanol generally increased during the frozen storage. In sensory test, the frozen soy yogurt prepared with a-chymotrypsin and mixed culture of B. bifidum and L. bulgaricus was the most desirable, the highest scores in sourness, bitterness and mouthfeel.

• Food Science of Animal Resources
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• v.18 no.1
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• pp.63-74
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• 1998

Recently the high outbreaks of intestinal disease caused by the consumption of frozen dairy foods containing pathogenic bacteria has generated considerable interest in the causative agent such as Listeria monocytogenes and E. coli O157:H7. This study was carried out to detect the above pathogens and compare the microbiological qualities of three commercial forzen yogurt products. The main results obtained were as follows. L. monocytogenes coliforms and E. coli O157:H7 were not detected in the total of seven frozen yogurt samples. For microbiological qualities the viable lactic counts of products manufactured by FA company were about 2.9$\times$108 -1.6$\times$109cfu/ml 1.7$\times$106 cfu/ml for FB's and 1.2$\times$106 cfu/ml for FC's The PH values of FA's FB's and FC's products was in the range of pH 4.1~5.3 and the values of FA's were 4.1~4.6 compared by the pH 5.2~5.3 of FB's and FC's products. During refrigeration of the test samples the survival rates of L. monocytogenes spiked into thawed frozen yogurt sample(FA's FB,s and FC's) were 0.55% 15.61% and 16.89% respectively. On the other hand E. coli O157:H7 and L. monocytogenes were 12.4% and 25.0% for FA's 10.8% and 20.8% for FB's and 10.26% and 22.7% for FC's under 37$^{\circ}C$ storage, As the results described above each frozen yogurt products were different in microbiological qualities. The survival rates of pathogens spiked into the samples increased with the pH of the products. This indicates that the pH or any other factors pre-sumable supressed the growth of E. coli O157:H7 and L. monocytogenes in frozen yogurt products.

• Korean Journal of Food Science and Technology
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• v.33 no.6
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• pp.676-681
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• 2001

This study was carried out to evaluate the quality characteristics of frozen soy yogurts prepared with different proteolytic enzymes and starter culture. The viable cell counts of lactic acid bacteria in frozen soy yogurts were measured $10^8$ CFU/g by the single culture method, while $10^9$ CFU/g by the mixed culture method except ${\alpha}-chymotrypsin$ treatment. The viable cell counts of lactic acid bacteria did not decrease after freezing for 30 min in ice cream maker. The lactic acid bacteria from the mixed culture showed better bile acid tolerance than those from the single culture. The lactic acid bacteria from the frozen soy yogurt prepared with ${\alpha}-chymotrypsin$ and mixed culture of Bifidobacterium bifidum and Lactobacillus bulgaricus showed better acid tolerance and bile acid tolerance. The highest(73.45%) overrun was observed in the frozen soy yogurt treated with ${\alpha}-chymotrypsin$ and mixed culture of B. bifidum and L. bulgaricus. The melt-down percent was higher in the single culture than the mixed culture. In sensory test, the frozen soy yogurt prepared with ${\alpha}-chymotrypsin$ and mixed culture of B. bifidum and L. bulgaricus was the most desirable, the highest scores in sourness, bitterness and mouthfeel.

• Proceedings of the Korean Society of Food and Cookery Science Conference
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• 1999.10a
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• pp.40-40
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• 1999

• Korean journal of food and cookery science
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• v.18 no.1
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• pp.43-50
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• 2002

This study was carried out to evaluate the quality attributes of frozen soy yogurts prepared by freezine soy yogurts, which are made of different types of Bifidobacteria (B. bifidum, B.breve, B. infantis) and oligosaccharides (fructooligosaccharides, galactooligosaccharides, isomaltooligosaccharides) containing $\alpha$-chymotrypsin treated soy protein isolate were evaluated in terms of overrun, melt-down quality, changes in the total number of Bifidobacteria after freezing, and sensory evaluation. The quality attributes of soy yogurts were also evaluated in terms of changes in the number of viable cells of Bifidobacteria in soy yogurts after incubation at 37$\^{C}$, pH 3.0 for 90 min, water holding capacity, and viscosity. The overrun of frozen soy yogurts fermented by B. bifidum showed the hiehest value but those fermented by B. infantis showed the lowest, while the melt-down quality of soy yogurts were vice versa. The total numbers of Bifidobacteria after freezing for 30 min in ice cream maker showed more than 10$\^$9/ CFU/ml. In sensory evaluation, all $\alpha$-chymotrypsin treated frozen soy yogsurt showed little beany flavor. In sour, sweet, and bitter tastes and mouth feel, the frozen soy yogurts fermented by B. bifidum evaluated better but those fermented by B. infantis evaluated worse. Also in the overall quality, the frozen soy yogurts fermented by B. bifidum were evaluated desirable but those fermented by B. infantis were evaluated undesirable. The water holding capacity and viscosity of soy yogurts fermented by B. bifidum showed the highest values but those fermented by B. infantis showed the lowest values. The total numbers of Bifidobacteria of all soy yogurts decreased from 10$\^$9/ CFU/ml to 10$\^$8/ CFU/ml after incubation at 37$\^{C}$, pH 3.0 for 90 min.

• Food preservation and processing industry
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• v.15 no.2
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• pp.23-31
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• 2016

Dairy products, including milk, cheese, cream, yogurt, and butter, constitute excellent sources of essential nutrients such as calcium, proteins, and vitamin D; therefore, nutritionists recommend a constant daily dietary intake of dairy products. Packaging is an important feature that ensures high-quality products are delivered to consumers; different packaging materials and forms are required depending on the products. Packaging forms include pouches for butter, cheese, and milk powder; cartons for liquid, frozen, and coagulated milk; packets for pasteurized liquid milk; bottles for milkshakes and other liquid products; and cups for frozen and coagulated products. The increase in mobile lifestyles among consumers will lead to smaller households and greater preference for convenience, which will promote individual and smaller packaging for dairy products. This article reviews the development of packaging materials and forms, packaging requirements, and future considerations for the packaging of dairy products.

• Korean Journal of Food Science and Technology
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• v.33 no.5
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• pp.603-610
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• 2001

The quality characteristics of soy yogurt prepared with different proteolytic enzymes and starter culture were evaluated. In order to facilitate the growth of lactic acid bacteria and subsequent production of lactic acid, soy protein isolate(SPI) was hydrolyzed using three kinds of proteases; one extracted from Aspergillus oryzae, bromelain and ${\alpha}-chymotrypsin$. The cultural systems employed thereafter for lactic fermentations were: 1) Bifidobacterium bifidum, 2) B. bifidum and Lactobacillus acidophilus, 3) B. bifidum and Lactobacillus bulgaricus. In soy yogurt, pH was more decreased by mixed culture method than single culture method with the accumulation of lactic acid. Viable cells of lactic acid bacteria in soy yogurts were measured $10^8$ CFU/g by the single culture method while $10^9$ CFU/g by the mixed culture method except ${\alpha}-chymotrypsin$ treatment. The amount of free amino acids in soy yogurts were substaintially increased by enzyme treatment. Viscosity was decreased by enzyme treatment, resulting in higher viscosity by ${\alpha}-chymotrypsin$ treatment. Water holding capacity was found to be higher in the single culture method in case of enzyme treatment. Among the various volatile flavor components isolated and identified after enzyme hydrolysis, acetaldehyde, ethanol, diacetyl, butyl alcohol contents tended to increase by lactic fermentation.